It is known that security connection will be established between two points across a public network using an exchange protocol of keys for the creation of a security connection. Such a protocol is described as SSL which is based on the data exchange thanks to a pair of keys, the public key and the private key for the definition of a symmetrical session encryption key. The data is codified by this session key, the latter being used only for this transaction.
This function can only be developed between two interlocutors and thus cannot allow the formation of a network for several users. In fact, it is necessary to have the same quantity of unities of dialogue as computers to connect.
The need to create such networks is present when one wishes to link several distant points but connected to a same public network such as Internet.
This need goes together with effective protection of the exchanged data because when one connects on the Internet, confidentiality is not guaranteed.
In this way an unsolved problem remains which consists of linking several computers or multimedia units through a public network at the same time guaranteeing the confidentiality of that data.